The result on Wednesday brings an end to what was at times a heated campaign. The vote itself had been criticised by same-sex marriage supporters, many of whom said it was unnecessary when parliament could debate the issue directly.

How did the vote unfold?

The survey was voluntary, unlike Australia's compulsory elections.

More than 12.7 million people - about 79.5% of eligible voters - took part in the eight-week poll, which asked one question: "Should the marriage law be changed to allow same-sex couples to marry?"

What has been the reaction?

"This is an amazing outcome and we should all be very proud of this amazing country," Qantas chief executive Alan Joyce, a prominent same-sex marriage supporter, told a jubilant crowd in Sydney.

Equality Campaign director Tiernan Brady told the BBC the result affirmed that Australia remained "the land of the fair go".

Former Prime Minister Tony Abbott, a high-profile same-sex marriage opponent, said parliament should respect the result.

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No campaigners have pledged to monitor the new parliamentary bill

He wrote on Facebook that he would support a bill that provided "freedom of conscience for all, not just the churches".

Another prominent No campaigner, Lyle Shelton, said: "We will now do what we can to guard against restrictions on freedom of speech and freedom of religion, to defend parents' rights, and to protect Australian kids from being exposed to radical LGBTIQ sex and gender education in the classrooms."

Why was the vote controversial?

The postal survey followed two failed attempts by the government to hold a compulsory national vote that was twice voted down by the Senate.

Senators who opposed the compulsory vote did not necessarily oppose legalisation, but said the vote would be costly and fuel hate campaigns. They argued the matter should be put to a parliamentary vote.

Many same-sex marriage advocates levelled the same criticism at the voluntary vote, which did not require legislative approval.